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Rollup merge of rust-lang#123005 - maurer:cfi-arbitrary-receivers, r=…
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…compiler-errors

CFI: Support complex receivers

Right now, we only support rewriting `&self` and `&mut self` into `&dyn MyTrait` and `&mut dyn MyTrait`. This expands it to handle the full gamut of receivers by calculating the receiver based on *substitution* rather than based on a rewrite. This means that, for example, `Arc<Self>` will become `Arc<dyn MyTrait>` appropriately with this change.

This approach also allows us to support associated type constraints as well, so we will correctly rewrite `&self` into `&dyn MyTrait<T=i32>`, for example.

r? `@workingjubilee`
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matthiaskrgr authored Mar 25, 2024
2 parents 5ce2a15 + 40f41e7 commit 4ccb5a7
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Showing 5 changed files with 115 additions and 39 deletions.
1 change: 1 addition & 0 deletions Cargo.lock
Original file line number Diff line number Diff line change
Expand Up @@ -4634,6 +4634,7 @@ dependencies = [
"rustc_session",
"rustc_span",
"rustc_target",
"rustc_trait_selection",
"tracing",
"twox-hash",
]
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1 change: 1 addition & 0 deletions compiler/rustc_symbol_mangling/Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ rustc_middle = { path = "../rustc_middle" }
rustc_session = { path = "../rustc_session" }
rustc_span = { path = "../rustc_span" }
rustc_target = { path = "../rustc_target" }
rustc_trait_selection = { path = "../rustc_trait_selection" }
tracing = "0.1"
twox-hash = "1.6.3"
# tidy-alphabetical-end
1 change: 1 addition & 0 deletions compiler/rustc_symbol_mangling/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,7 @@
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![doc(rust_logo)]
#![feature(rustdoc_internals)]
#![feature(let_chains)]
#![allow(internal_features)]

#[macro_use]
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109 changes: 70 additions & 39 deletions compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ use rustc_data_structures::base_n;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir as hir;
use rustc_middle::ty::layout::IntegerExt;
use rustc_middle::ty::TypeVisitableExt;
use rustc_middle::ty::{
self, Const, ExistentialPredicate, FloatTy, FnSig, Instance, IntTy, List, Region, RegionKind,
TermKind, Ty, TyCtxt, UintTy,
Expand All @@ -21,7 +22,9 @@ use rustc_span::sym;
use rustc_target::abi::call::{Conv, FnAbi, PassMode};
use rustc_target::abi::Integer;
use rustc_target::spec::abi::Abi;
use rustc_trait_selection::traits;
use std::fmt::Write as _;
use std::iter;

use crate::typeid::TypeIdOptions;

Expand Down Expand Up @@ -1113,51 +1116,46 @@ pub fn typeid_for_instance<'tcx>(
instance.args = strip_receiver_auto(tcx, instance.args)
}

if let Some(impl_id) = tcx.impl_of_method(instance.def_id())
&& let Some(trait_ref) = tcx.impl_trait_ref(impl_id)
{
let impl_method = tcx.associated_item(instance.def_id());
let method_id = impl_method
.trait_item_def_id
.expect("Part of a trait implementation, but not linked to the def_id?");
let trait_method = tcx.associated_item(method_id);
if traits::is_vtable_safe_method(tcx, trait_ref.skip_binder().def_id, trait_method) {
// Trait methods will have a Self polymorphic parameter, where the concreteized
// implementatation will not. We need to walk back to the more general trait method
let trait_ref = tcx.instantiate_and_normalize_erasing_regions(
instance.args,
ty::ParamEnv::reveal_all(),
trait_ref,
);
let invoke_ty = trait_object_ty(tcx, ty::Binder::dummy(trait_ref));

// At the call site, any call to this concrete function through a vtable will be
// `Virtual(method_id, idx)` with appropriate arguments for the method. Since we have the
// original method id, and we've recovered the trait arguments, we can make the callee
// instance we're computing the alias set for match the caller instance.
//
// Right now, our code ignores the vtable index everywhere, so we use 0 as a placeholder.
// If we ever *do* start encoding the vtable index, we will need to generate an alias set
// based on which vtables we are putting this method into, as there will be more than one
// index value when supertraits are involved.
instance.def = ty::InstanceDef::Virtual(method_id, 0);
let abstract_trait_args =
tcx.mk_args_trait(invoke_ty, trait_ref.args.into_iter().skip(1));
instance.args = instance.args.rebase_onto(tcx, impl_id, abstract_trait_args);
}
}

let fn_abi = tcx
.fn_abi_of_instance(tcx.param_env(instance.def_id()).and((instance, ty::List::empty())))
.unwrap_or_else(|instance| {
bug!("typeid_for_instance: couldn't get fn_abi of instance {:?}", instance)
});

// If this instance is a method and self is a reference, get the impl it belongs to
let impl_def_id = tcx.impl_of_method(instance.def_id());
if impl_def_id.is_some() && !fn_abi.args.is_empty() && fn_abi.args[0].layout.ty.is_ref() {
// If this impl is not an inherent impl, get the trait it implements
if let Some(trait_ref) = tcx.impl_trait_ref(impl_def_id.unwrap()) {
// Transform the concrete self into a reference to a trait object
let existential_predicate = trait_ref.map_bound(|trait_ref| {
ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef::erase_self_ty(
tcx, trait_ref,
))
});
let existential_predicates = tcx.mk_poly_existential_predicates(&[ty::Binder::dummy(
existential_predicate.skip_binder(),
)]);
// Is the concrete self mutable?
let self_ty = if fn_abi.args[0].layout.ty.is_mutable_ptr() {
Ty::new_mut_ref(
tcx,
tcx.lifetimes.re_erased,
Ty::new_dynamic(tcx, existential_predicates, tcx.lifetimes.re_erased, ty::Dyn),
)
} else {
Ty::new_imm_ref(
tcx,
tcx.lifetimes.re_erased,
Ty::new_dynamic(tcx, existential_predicates, tcx.lifetimes.re_erased, ty::Dyn),
)
};

// Replace the concrete self in an fn_abi clone by the reference to a trait object
let mut fn_abi = fn_abi.clone();
// HACK(rcvalle): It is okay to not replace or update the entire ArgAbi here because the
// other fields are never used.
fn_abi.args[0].layout.ty = self_ty;

return typeid_for_fnabi(tcx, &fn_abi, options);
}
}

typeid_for_fnabi(tcx, fn_abi, options)
}

Expand All @@ -1183,3 +1181,36 @@ fn strip_receiver_auto<'tcx>(
};
tcx.mk_args_trait(new_rcvr, args.into_iter().skip(1))
}

fn trait_object_ty<'tcx>(tcx: TyCtxt<'tcx>, poly_trait_ref: ty::PolyTraitRef<'tcx>) -> Ty<'tcx> {
assert!(!poly_trait_ref.has_non_region_param());
let principal_pred = poly_trait_ref.map_bound(|trait_ref| {
ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref))
});
let mut assoc_preds: Vec<_> = traits::supertraits(tcx, poly_trait_ref)
.flat_map(|super_poly_trait_ref| {
tcx.associated_items(super_poly_trait_ref.def_id())
.in_definition_order()
.filter(|item| item.kind == ty::AssocKind::Type)
.map(move |assoc_ty| {
super_poly_trait_ref.map_bound(|super_trait_ref| {
let alias_ty = ty::AliasTy::new(tcx, assoc_ty.def_id, super_trait_ref.args);
let resolved = tcx.normalize_erasing_regions(
ty::ParamEnv::reveal_all(),
alias_ty.to_ty(tcx),
);
ty::ExistentialPredicate::Projection(ty::ExistentialProjection {
def_id: assoc_ty.def_id,
args: ty::ExistentialTraitRef::erase_self_ty(tcx, super_trait_ref).args,
term: resolved.into(),
})
})
})
})
.collect();
assoc_preds.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder()));
let preds = tcx.mk_poly_existential_predicates_from_iter(
iter::once(principal_pred).chain(assoc_preds.into_iter()),
);
Ty::new_dynamic(tcx, preds, tcx.lifetimes.re_erased, ty::Dyn)
}
42 changes: 42 additions & 0 deletions tests/ui/sanitizer/cfi-complex-receiver.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
// Check that more complex receivers work:
// * Arc<dyn Foo> as for custom receivers
// * &dyn Bar<T=Baz> for type constraints

//@ needs-sanitizer-cfi
// FIXME(#122848) Remove only-linux once OSX CFI binaries work
//@ only-linux
//@ compile-flags: --crate-type=bin -Cprefer-dynamic=off -Clto -Zsanitizer=cfi
//@ compile-flags: -C target-feature=-crt-static -C codegen-units=1 -C opt-level=0
//@ run-pass

use std::sync::Arc;

trait Foo {
fn foo(self: Arc<Self>);
}

struct FooImpl;

impl Foo for FooImpl {
fn foo(self: Arc<Self>) {}
}

trait Bar {
type T;
fn bar(&self) -> Self::T;
}

struct BarImpl;

impl Bar for BarImpl {
type T = i32;
fn bar(&self) -> Self::T { 7 }
}

fn main() {
let foo: Arc<dyn Foo> = Arc::new(FooImpl);
foo.foo();

let bar: &dyn Bar<T=i32> = &BarImpl;
assert_eq!(bar.bar(), 7);
}

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